Cyanine dyestuff intermediates



Patented Apr. 3, 1945 UNITED STATES CYANINE DYESTUFF INTERMEDIATES John David Kendall, Henry Walter Wood, and

John Raymond Majer, Ilford, England, assignors to Ilford Limited, Ilford, Essex, England, a

British company No Drawing. Application October 8, 1942, Serial No. 461,322. In Great Britain November 6,

11 Claims. (or; 260-240) This invention relates to the production of new organic compounds which are of value as intermediates in the manufacture of dyestuffs.

Processes are already known for the manufacture of organic compounds of the general Formula I:

D R2 CORz where D is the residue of a heterocyclic nitrogen nucleus, R1 is an alkyl or aralkyl group, R2 is a hydrogen atom or an alkyl or aralkyl group, R3 and R4 are hydrocarbon groups, e. g. alkyl, aryl or aralkyl groups, n is nought or 1 and m is 1, 3 or 5. Thus compounds of the general Formula I where m is 1 may be prepared by reacting an alkyl or aralkyl quaternary salt of a heterocyclic nitrogen compound containing an w-acetanilidovinyl group in the a or 7 position to the heterocyclic nitrogen atom with a 1.3-diketone of the formula R3.CO.CH2.CO.R4 (II) verting compounds of the type of s O c=on-ooom CHa to the corresponding thio compounds of the type C=CH-CSCH:

These processes consist in directly heating the former compound with phosphorus pentasulphide or treating the former compound with phosphorus pentachloride and then with thioacetamide. It has been found that neither of these processes is effective in converting compounds of general formula I to the corresponding thione compounds.

It has now been discovered, however, and this forms the basis of the present invention, that compounds of general Formula'I may be readily converted to corresponding compounds contain-- 5 ing reactive thioether groups by treating with 'an alkylor aralkyl-mercaptan in the presence of a strong acid or an alkylsalt of a strong acid. The reaction may be effected inthe presence of a solvent for the reactants; however, if a hydroxylic solvent is employed there results some hydrolysis of the compounds of general Formula I to the corresponding mono-acylated compounds. In order to reduce as much as possible this tendency to hydrolysis, the reagents are preferably used as dry as possible. A very convenient acid'to use is dry hydrochloric acid gas. Any excess of this remaining at the end of the reaction is capable of removal under reduced pres- COR:

+ BK RaSH The applicants new intermediates are believed to have general Formula VI. It is clear that the reaction does not depend on an initial hydrolysis of the compound of general Formula I to the mono-acylated compound from the fact that treatment of the mono-acylated compound with an alkyl mercaptan and an acid does not produce the thio compound, the original material being 60 obtained unchanged.

The new intermediates of general Formula VI may readily be isolated from any acylated products produced by hydrolysi of the compounds of general Formula I since the new intermediates are more soluble in ethyl and methyl alcohol. The new intermediates arequite stable in such alcoholic solution and evaporation of, the alcohol under reduced pressure yields the intermediates in solid form.

Referring to the formulae set forthabove, the residue D may be the residue or ari heterocyclic nitrogen compound, e. g. the residue of any of the heterocyclic nitrogen compounds commonly employed in the manufacture of cyanine dyestuffs such as the substituted and unsubstituted thiazoles, thiazolines, oxazoles, oxazolines, selenazoles, selenazolines, pyridine, quinoline, indolenine, diazines (e. g. pyrimidine) thio-diazoles and quinazoline and the corresponding substituted or unsubstituted polycyclic compounds such as benzthiaz'oles, naphthathiazole's and anthrathiazoles and also the diazines described in Specification No. 425,609. I

The groups R1, Rz, R3, R4 and R may variously behydrogenatomsalkyl groups, aryl groups and aralkyl groups as above defined. R1 is preferablya lower alkylgroup, i. e. a methyl, ethyl, propyl or butyl group,or, if an aralkyl group,

is preferably, a penz ylgr up T e p R2 may, be a hydrogen atom, but if not, is preferablya lower alkyl group as defined above. It may, however, be a higher alkyl group or an aralkyl group such as benzyl. R3 and R4 are preferably lower k l.v r p t o gh, he may be higher aik'yl rou s. preml l mu se in t ase of the group R2 or the maybe aryl groups. The group R5 is preferably ,a lower, alkyl group since the lower alkyl mercaptans are more easily reactive alkyl, aryl or arallgylg'roups may themselves contain substituent groups, e. g. hydroxy or amino groups.

As indicated above, dry hydrochloric acid gas is a very convenient acid to employ in the process of this invention. However, other strong acids may be employed, e. g. other hydrohalic'"acids, nitric acid, sulphuric acid, or pliosphoricfacid, onstrong organic acids, e. g. p-toluene-sulphonic acid, or alkyl salts of such acids, e. g. alkyl halides such as methyl iodide.

The intermediates obtained by the process of the present invention are in the form of quaternary salts and it is to be understood that they may be converted to quaternary salts 'of other acids by treatment with suitable'salts ofsuch other acids, e. g. alkali metal salts. Thusjintermediates obtained as chlorides may be converted to'bromides or iodidesby treatment with potassium bromide or potassium iodide.

The following examples illustrate the invention:

Example 1 Preparationof'thedyestuff intermediate of the probable formula 7.5 gms. of 1-(w-diacetyl-propenylidene)-2 methyl-dihydrobenzthiazole, 30 cos. of methyl alcohol and 10 cos. of ethyl mercaptan were mixed together and cooled. Dry hydrochloric acid gas was passed through the mixture for 2 hours and the mixture was then allowed to stand for 24 hours, On evaporating the clear solution in a vacuum desiccator, the product was obtained as a slightly sticky brown solid.

The corresponding N-ethyl derivative may be similarly prepared and is also a sticky brown solid.

Example 2 Preparation of the dyestuff intermediate of the probable formula:

Clix /CH2 /C SCzHs o-on=on-on=c \N CH: om Cl resulted which changed to an Oilafter standing overnight. This was separatedand dried in vacuum desiccator until it crystallised out.; lt waspurified by refluxing it with cos. of dry ethyl acetate, theproduct separating on cooling a's t pastyjmass which solidified to 'a purplej'solid. alternative method of preparing dye consistsln mixing 1'5 gms.;er the said indolerfir'ie compound with 50 cos. pffethyl mercaptan,

the mixture, allowing the mixture to stand then evaporating off the excess mercaptan, leaving the desired dyestuff intermediate.

Example 3 Preparation of the dyestuff intermediate of the probable formula:

"scan together and dry hydrochloric 'acid'ga's was passed through the mixture until the suspended solid went into solution. The process was continued untilan orange solid began. to precipitate and the solution turned orange. This precipitate was removed by filtration and consisted of1;6=dimethyl-2- (w-acetyl-propenylidene) -1.'2-'dihydroquinoline. The filtrate was then evaporated to dryness under reduced-pressure and yielded'tlie desired dye'stufi-intermediate as-a reddish brown solid melting at 74 C. 5

, reissue g o,fiiiiaiit st i dw a ifiasamta s prolfible'formula: g

on; 2cm

o-crr=on-cn=c--solnl H v 'Cs \I 11 gms. of 2-(w-diacetyl-propenylidene)-1.3.3-

Preparation of the dyestuffintermediate of the probable formula 9 gins. of 1-( w-diacetyl-propenylidene) -2-methyldihydro benzselenazole and cos. ethyl mercaptan were mixed together, and 3 gins. dry HCl gas was passed through the mixture. The solid dissolved and the mixture was allowed to ,stand for three days. Excess mercaptan was then removed, leaving the desired dyestufi intermediate as a light brown sticky solid.

Example 6' 7 Preparation of the dyestuif intermediate of the probable formula:

S s cm.

ocn=o -on=o CHI 6 gms. of 1-( w-diacetyl-propenylidenel -2-,c-hydroxy-ethyl-dihydro-benzthiazole and 50 cos. of ethyl mercaptan were mixed together and cooled, 1.5 gms. of dry hydrochloric acid gas was passed through the mixture and the mixturewas then allowed to stand for 3 days. The excess mercaptan was then distilled ofi leaving the desired dyestufi intermediate (after drying in a vacuum desiccator) as a sticky orange-brown solid.

attests I "E'zamgile'l' Preparation of the dyestuil intermediate probable formula:

0E3 CAB:

-c-cn=on-on=0 1,

i718 'of -2 (zu dipropionyl -propenylidene) 1.3.3-trimethyl indolenine were mixed with -l-llil cos. of ethyl mercaptan and 8- gm-s -of'methyl iodide was added. The mixture wasallowed to stand for a week during which a red oily layer separated. This was removed and the'excess rnercaptand-isti-lled ofi,yielding the desired ldye 'stuffintennediate -asa red-solid. a a

teririedi-ates which comprises reacting a oompound of the general 'formula:

where D is'the i'e'sidueo'f a heterocyclic nitrogen compound of the type used in cyariinedyes, R1 is selected from theclass consisting of alkyl and aralykyl groups, R2 isse'le'cted from the class consisting of hydrogen atoms and alkyland aralkyl groups, and n is selected from the class consisting of nought and 1 with a substance selected from the class consisting of alkyl and aralkyl ofthe mercaptans in the presence of a substance selected from the class consisting of strong mineral acids and alkyl salts thereof.

2. A process for the production of dyestufl 111- termediates which comprises reacting a compound of the general formula:

where D is the residue of a heterocyclic nitrogen compound of the type used in cyanine dyes, R1 is selected from the class consisting of alkyl and aralkyl groups, and n is selected from the class consisting of nought and 1 with a lower alkyl mercaptan in the substantial absence of any hydroxylic substance and in the presence of a substance selected from the class consisting of strong mineral acids and alkyl salts thereof.

3. A process for the production of dyestufi intel-mediates which comprises reacting a compound of the general formula:

D C0.Alkyl 1 -:-(cn=cH =0H-0H=0\ R1 C0.Alkyl where D is the residue of a heterocyclic nitrogen compound of the type used in cyanine dyes, R1 is selected from the class consisting of alkyl and aralkyl groups, and n is selected from the class consisting of nought and 1 with a lower alkyl mercaptan, in the substantial absence of any hydroxylic substance and in the presence of dry hydrochloric acid gas.

inulaz sisting of nought and 1, and A is an acid residue. 5. A- dyestufi intermediate or the general for- CH=C where D is the residue of a heterocyclic nitrogen compound of the type used in cyanine dyes, R1 is selected from the class consisting of alkyl and aralkyl groups, R: and Rs are each alkyl groups, nis selected from the class consisting of nought and 1, and A is an acid residue.

6. A process for the production of dye intermediates which comprises reacting l-(omega diacctyl propenylidine) 2 methyl dihydro benzthiazole with ethyl mercaptan in the presence of dry hydrochloric acid gas.

" "Z. A dyestufi intermediate of the formula:

CH: C]

8. A process for the production of dyestufl intermediates which comprises reacting 2 -(omega diacetyl propenylidine) 1.3.3 trimethylindolenine with ethyl mercaptan in the presence of dry hydrochloric acid gas.

9. A dyestufl intermediate of the formula:

10. A process for the production or dyestuii tel-mediates which comprises reacting l-(ome'ga .diacetyl propenylidine) 2 4 methyl benzselenazole with ethyl mercaptan in the ence of dry hydrochloric acid gas. 11. A dyestufl intermediate of the formula:

pres:

SCsHl JOHN DAVID KENDALL.

HENRY WALTER WOOD. JOHN RAYMOND MAJER.

CERTIFICATE OF CORRECTION. Patent No. 2,572,950. April 5, 1915.

JOHN DAVID KENDALL, ET AL.

It is hereby certified that error appears in the Printed p i ation of the above numbered patent requiring Correction follows: ag S cond column, line 11, claim 9, for that p r i n f the formula reading "SO H read -SC H and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 11th day 0f September, A.- D. 19LL5.

Leslie Frazer (Seal) First Assistant Commissioner of Patents. 

